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CVE-2026-72206
ntfs: validate index block header more strictly
Published 2026-08-15 (2 months ago) by the Linux kernel CNA. Subsystem fs/ntfs. Debian urgency: unimportant.
What to do, per Debian release
Debian's own status for CVE-2026-72206 in every release this site tracks, and what each one means in practice. Every status below is the one the Debian Security Team publishes for this CVE. source
| Release | Status | Version | What this means |
|---|---|---|---|
| Debian 12bookworm | not affected | 6.1.190-1 | Nothing to do. bookworm never shipped the vulnerable code. |
| Debian 13trixie | not affected | 6.12.113-1 | Nothing to do. trixie never shipped the vulnerable code. |
| Debian 14forky | fixed | 7.1.5-1 | Update the kernel and reboot. Fixed in 7.1.5-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.1.5-1 | Update the kernel and reboot. Fixed in 7.1.5-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
Modify ntfs_index_block_inconsisent() to perform stricter validation of INDEX_HEADER geometry in INDX blocks, and update ntfs_lookup_inode_by_name() to use that function to validate INDX blocks.
Where it lives
The fix touches these files. If the subsystem is one you do not use, the practical exposure is lower, though the package is still the vulnerable one.
fs/ntfs/dir.c
fs/ntfs/index.c
fs/ntfs/index.h
- What this is
- NTFS FILESYSTEMMAINTAINERS section matched on fs/ntfs/ · linux-fsdevel@vger.kernel.org · Maintained
- Kernel module
- ntfs
Check it on the machine
grep -w CONFIG_NTFS_FS /boot/config-$(uname -r)Reads the booted kernel's own configuration, on the machine and nowhere else. =y is built in, =m is a module, and an is not set line means the code is not there.
lsmod | grep -w ntfsPrints a line if that module is loaded right now, and nothing if it is not. One that is not loaded can still be loaded later by anything that needs it.
Show whether Debian builds this, per release
Debian does not build this code in 1 release. It does build it in 2 releases, so the answer depends on which release the machine runs. The build rule could not be established for 1 release, so nothing is claimed about those.
- bookwormn
- trixie?
- forky, sidm
- n
- not enabled on any flavour - this release does not build the code
- ?
- not established - no Makefile entry for the affected file
- m
- a loadable module on every flavour - check lsmod, can be blacklisted
Where a release above reads "not established", no build rule for the affected file was found in that release's kernel tree. That is a gap in this lookup, not a finding that the code is absent.
- Build switch
- CONFIG_NTFS_FS
From the configuration Debian publishes for every kernel flavour it builds. It covers only the architectures Debian ships a linux-config package for, and nothing about a kernel you built yourself. Debian's own status above stays authoritative about the source package.MAINTAINERS kbuild Makefiles Debian linux-config packages
Signals
- Published
- 2026-08-15 (2 months ago)source
- CVSS
- 9.8 critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:Hsource recompute it - Attack vector
- network (AV:N)source
- EPSS
- 0.55%, higher than 45.0% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- unimportantsource
- Subsystem
- fs/ntfs
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 7.1 | 7.1.5 | 34a49b3e94a5 |
| 7.1 | 7.2 | 14bc34fe9485 |
Why the CNA scored it this way
Quoted from the kernel CNA's own scoring file, word for word. A highlighted metric carries the most severe value CVSS v3.1 defines for it, which is what pushes the score up. source
- AV:NAttack vector, network
- Legacy fs/ntfs registers ntfs_export_ops; remote nfsd/ksmbd LOOKUP or open/stat on an exported crafted NTFS volume reaches ntfs_lookup→ntfs_lookup_inode_by_name INDX B+tree descent without attacker local shell access.
- AC:LAttack complexity, low
- The attacker fully controls on-disk INDX INDEX_HEADER geometry (entries_offset, index_length, allocated_size); pre-fix ntfs_lookup_inode_by_name omitted checks that ntfs_index_block_inconsistent enforced, enabling reliable malformed-index parsing with no race.
- PR:NPrivileges required, none
- Exploitation needs only a malicious NTFS image (USB, loop, dual-boot) mounted by root/udisks2/automount, or NFS/SMB read access to exported paths; no init-namespace root or CAP_SYS_ADMIN on the lookup trigger path.
- UI:NUser interaction, none
- Automounting removable NTFS or fill_super lookups (e.g. into $Extend/Quota) invoke ntfs_lookup_inode_by_name against index-allocation blocks without further victim action beyond presenting the crafted volume.
- S:UScope, unchanged
- Out-of-bounds INDX parsing impacts only the host kernel within its filesystem security authority; this is not a VM escape, IOMMU bypass, or cross-sandbox boundary crossing.
- C:HConfidentiality impact, high
- Missing entries_offset/index_length versus bytes_available validation lets lookup reinterpret INDX header bytes as index entries and read past the index area within the kmalloc page buffer into adjacent kernel memory.
- I:HIntegrity impact, high
- The same unchecked INDX geometry is parsed by ntfs_ib_read for write-capable index operations; attacker-steerable header/entry walks can feed later memmove/insert paths and heap corruption beyond the intended index buffer.
- A:HAvailability impact, high
- Crafted INDX entries_offset/length fields can cause infinite index-entry loops, slab/page out-of-bounds reads on malformed walks, or unhandled faults that oops or panic the kernel during directory lookup or mount.